The invention relates to a dental impression tray for an optional partially toothless jaw and for a toothless jaw with implants on optional places, which is used for taking and producing impressions for dentures.
The technical problem to be solved by the present invention is how to make an impression tray that will make possible and ensure doctrinally correct impressions of toothless jaw sections as well as of jaw sections with teeth optionally arranged thereon, thereby excluding the possibility of breaking the impressed remaining teeth or implants on the intermediate mold due to the negative angles between the impression material and the cast model.
There is known an impression tray for partially toothless jaw and toothless jaw with implants, which is basically executed as a horseshoe-shaped U-profile.
A drawback of this tray at the application on a partially toothless jaw lies in the fact that a larger quantity of the impression material than really needed must be used in the groove in the area of the toothless jaw section. This represents an unnecessary cost. A further disadvantage is the fact that such increased quantity of impression material excludes the application of some kinds of impression materials.
Since at the process of impression production the toothless jaw section reacts (deforms) differently from the jaw section with hard tissue, an impression is received, which does not represent the real supporting surface for the denture.
If this impression tray is used at the production of the impression of a partially toothless jaw, it is rather likely that at taking off (shelling off) the intermediate mold will break in the area of teeth or implants because of negative angles thereon. In such case the intermediate mold has to be repaired, whereat errors can occur. Any corrections represent additional work and cost.
A further known impression tray for partially toothless jaw and toothless jaw with implants consists of an impression tray for toothless jaw, to which at a previously defined place or places a supplement is added for the jaw section with teeth or implants.
Thus the above-mentioned drawback is partially eliminated. This impression tray at toothless sections rests correctly on the alveolar ridge and at sections with teeth its excavated hollow makes possible an appropriate impression.
An essential drawback of this impression tray is that it is only applicable at single defined arrangements of teeth or implants in the jaw. Such trays are only produced for the most frequent arrangements of teeth, i.e. for upper and lower front teeth.
Since there exist many atypical arrangements of teeth and implants in the jaw, it is obviously impossible to produce trays for all possible cases on an industrial scale and at an adequate price. Nor is it sensible for a dentist to possess such a number of different trays as they tie up too much money, occupy too much room and, last but not least, are not fully suitable.
Furthermore it is known that some impression materials are specially suited for a good impression of the toothless jaw and other impression materials for the impression of hard tissues making possible the taking off of the intermediate mold of the impression section also in an area with negative angles.
In view of the above-described different characteristics of the impression materials for the toothless jaw and the jaw with hard tissue, at the application of this impression tray the exclusive nature of the chosen impression material shows as a good impression on toothless jaw section or as later undamaged taking off the intermediate mold of the impression section, respectively.
Therefore there appears a need, though in a relatively small number of teeth states, for the application of two different impression materials, i.e. the material for the toothless jaw and the material for hard tissues.
Known impression trays do not make possible such application.